If you want to see all photos in the order they have been taken, you may want to use the "All Photos" tab.
The missing "days" and "Recents" are indeed making Photos more difficult to use, when the Photos Library is large. But there are also some benefits of the new design. Apple has listened to the users and added the ability to rearrange the user interface. We can now pin the collections we are using frequently for easy access, and best of all, remove collections from the interface, that we do not want to use at all. This page in the user guide describes, how we can rearrange the collection, remove unwanted items, and pin the ones we frequently need: Customize the Photos app on iPhone - Apple Support
Try to make the best of the new "Customize & Reorder" command.